Do you think it is worth the extra complexity of browser-detecting and loading the original JS if the browser has actual ES6 generator support? Firefox has it now without requiring any flags. Chrome(/Opera)/Node require --harmony or --harmony-generators.
I might recommend against the additional complexity for most use cases, since the generated code is only 1.5x slower, but I fully expect/hope that Facebook will decide to bite that complexity bullet for the speed gains in newer browsers. Betting on the future of JS is very much the ethos here.
Any interest at FB to sponsor the JSC implementation? That would leave IE as the odd one out... (If anyone reading works at Microsoft, politely ask the IE team to prioritize ES6 generators :))
